/*      $Id: at91usart.c,v 1.14 2022/10/26 23:38:06 riastradh Exp $     */
/*      $NetBSD: at91usart.c,v 1.14 2022/10/26 23:38:06 riastradh Exp $ */

/*
 * Copyright (c) 2007 Embedtronics Oy. All rights reserved.
 *
 * Copyright (c) 1998, 1999, 2001, 2002, 2004 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jesse Off
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Ichiro FUKUHARA and Naoto Shimazaki.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by IWAMOTO Toshihiro.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright (c) 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)com.c       7.5 (Berkeley) 5/16/91
 */

/*
 * TODO: hardware flow control
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: at91usart.c,v 1.14 2022/10/26 23:38:06 riastradh Exp $");

#include "opt_kgdb.h"

#ifdef RND_COM
#include <sys/rndsource.h>
#endif

#ifdef  NOTYET
/*
 * Override cnmagic(9) macro before including <sys/systm.h>.
 * We need to know if cn_check_magic triggered debugger, so set a flag.
 * Callers of cn_check_magic must declare int cn_trapped = 0;
 * XXX: this is *ugly*!
 */
#define cn_trap()                               \
        do {                                    \
                console_debugger();             \
                cn_trapped = 1;                 \
        } while (/* CONSTCOND */ 0)
#endif  /* NOTYET */


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/tty.h>
#include <sys/uio.h>
#include <sys/vnode.h>
#include <sys/kauth.h>

#include <machine/intr.h>
#include <sys/bus.h>

#include <ddb/db_active.h>

#include <arm/at91/at91reg.h>
#include <arm/at91/at91var.h>
#include <arm/at91/at91usartreg.h>
#include <arm/at91/at91usartvar.h>

#include <dev/cons.h>

static int      at91usart_param(struct tty *, struct termios *);
static void     at91usart_start(struct tty *);
static int      at91usart_hwiflow(struct tty *, int);

#if 0
static u_int    cflag2lcrhi(tcflag_t);
#endif
static void     at91usart_set(struct at91usart_softc *);

#if     NOTYET
int             at91usart_cn_getc(dev_t);
void            at91usart_cn_putc(dev_t, int);
void            at91usart_cn_pollc(dev_t, int);
void            at91usart_cn_probe(struct consdev *);
void            at91usart_cn_init(struct consdev *);

static struct at91usart_cons_softc {
        bus_space_tag_t         sc_iot;
        bus_space_handle_t      sc_ioh;
        bus_addr_t              sc_hwbase;
        int                     sc_ospeed;
        tcflag_t                sc_cflag;
        int                     sc_attached;

        uint8_t                 *sc_rx_ptr;
        uint8_t                 sc_rx_fifo[64];
} usart_cn_sc;

static struct cnm_state at91usart_cnm_state;
#endif  /* NOTYET */

static void     at91usart_soft(void* arg);
inline static void      at91usart_txsoft(struct at91usart_softc *, struct tty *);
inline static void      at91usart_rxsoft(struct at91usart_softc *, struct tty *, unsigned csr);

#define PDC_BLOCK_SIZE  64

//CFATTACH_DECL_NEW(at91usart, sizeof(struct at91usart_softc),
//            at91usart_match, at91usart_attach, NULL, NULL);

//#define       USART_DEBUG     10

#ifdef  USART_DEBUG
int usart_debug = USART_DEBUG;
#define DPRINTFN(n,fmt) if (usart_debug >= (n)) printf fmt
#else
#define DPRINTFN(n,fmt)
#endif

extern struct cfdriver at91usart_cd;

dev_type_open(at91usart_open);
dev_type_close(at91usart_close);
dev_type_read(at91usart_read);
dev_type_write(at91usart_write);
dev_type_ioctl(at91usart_ioctl);
dev_type_stop(at91usart_stop);
dev_type_tty(at91usart_tty);
dev_type_poll(at91usart_poll);

const struct cdevsw at91usart_cdevsw = {
        .d_open = at91usart_open,
        .d_close = at91usart_close,
        .d_read = at91usart_read,
        .d_write = at91usart_write,
        .d_ioctl = at91usart_ioctl,
        .d_stop = at91usart_stop,
        .d_tty = at91usart_tty,
        .d_poll = at91usart_poll,
        .d_mmap = nommap,
        .d_kqfilter = ttykqfilter,
        .d_discard = nodiscard,
        .d_flag = D_TTY
};

#if     NOTYET
struct consdev at91usart_cons = {
        at91usart_cn_probe, NULL, at91usart_cn_getc, at91usart_cn_putc, at91usart_cn_pollc, NULL,
        NULL, NULL, NODEV, CN_REMOTE
};
#endif  /* NOTYET */

#ifndef DEFAULT_COMSPEED
#define DEFAULT_COMSPEED 115200
#endif

#define COMUNIT(x)      TTUNIT(x)
#define COMDIALOUT(x)   TTDIALOUT(x)

#define COM_ISALIVE(sc) ((sc)->enabled != 0 && device_is_active((sc)->sc_dev))

static inline void
at91usart_writereg(struct at91usart_softc *sc, int reg, u_int val)
{
        bus_space_write_4(sc->sc_iot, sc->sc_ioh, reg, val);
}

static inline u_int
at91usart_readreg(struct at91usart_softc *sc, int reg)
{
        return bus_space_read_4(sc->sc_iot, sc->sc_ioh, reg);
}
#if 0
static int
at91usart_match(device_t parent, cfdata_t cf, void *aux)
{
        if (strcmp(cf->cf_name, "at91usart") == 0)
                return 1;
        return 0;
}
#endif
static int at91usart_intr(void* arg);

void
at91usart_attach_subr(struct at91usart_softc *sc, struct at91bus_attach_args *sa)
{
        struct tty *tp;
        int err;

        printf("\n");

        if (bus_space_map(sa->sa_iot, sa->sa_addr, sa->sa_size, 0, &sc->sc_ioh))
                panic("%s: Cannot map registers", device_xname(sc->sc_dev));

        sc->sc_iot = sa->sa_iot;
        sc->sc_hwbase = sa->sa_addr;
        sc->sc_dmat = sa->sa_dmat;
        sc->sc_pid = sa->sa_pid;

        /* allocate fifos */
        err = at91pdc_alloc_fifo(sc->sc_dmat, &sc->sc_rx_fifo, AT91USART_RING_SIZE, BUS_DMA_READ | BUS_DMA_STREAMING);
        if (err)
                panic("%s: cannot allocate rx fifo", device_xname(sc->sc_dev));

        err = at91pdc_alloc_fifo(sc->sc_dmat, &sc->sc_tx_fifo, AT91USART_RING_SIZE, BUS_DMA_WRITE | BUS_DMA_STREAMING);
        if (err)
                panic("%s: cannot allocate tx fifo", device_xname(sc->sc_dev));

        /* initialize uart */
        at91_peripheral_clock(sc->sc_pid, 1);

        at91usart_writereg(sc, US_IDR, -1);
        at91usart_writereg(sc, US_RTOR, 12);    // 12-bit timeout
        at91usart_writereg(sc, US_PDC + PDC_PTCR, PDC_PTCR_TXTDIS | PDC_PTCR_RXTDIS);
        at91_intr_establish(sa->sa_pid, IPL_TTY, INTR_HIGH_LEVEL, at91usart_intr, sc);
        USART_INIT(sc, 115200U);

#ifdef  NOTYET
        if (sc->sc_iot == usart_cn_sc.sc_iot
            && sc->sc_hwbase == usart_cn_sc.sc_hwbase) {
                usart_cn_sc.sc_attached = 1;
                /* Make sure the console is always "hardwired". */
                delay(10000);   /* wait for output to finish */
                SET(sc->sc_hwflags, COM_HW_CONSOLE);
                SET(sc->sc_swflags, TIOCFLAG_SOFTCAR);
                SET(sc->sc_ier, USART_INT_RXRDY);
                USARTREG(USART_IER) = USART_INT_RXRDY; // @@@@@
        }
#endif  // NOTYET

        tp = tty_alloc();
        tp->t_oproc = at91usart_start;
        tp->t_param = at91usart_param;
        tp->t_hwiflow = at91usart_hwiflow;

        sc->sc_tty = tp;

        tty_attach(tp);

#if     NOTYET
        if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                int maj;

                /* locate the major number */
                maj = cdevsw_lookup_major(&at91usart_cdevsw);

                cn_tab->cn_dev = makedev(maj, device_unit(sc->sc_dev));

                aprint_normal("%s: console (maj %u  min %u  cn_dev %u)\n",
                    device_xname(sc->sc_dev), maj, device_unit(sc->sc_dev),
                    cn_tab->cn_dev);
        }
#endif  /* NOTYET */

        sc->sc_si = softint_establish(SOFTINT_SERIAL, at91usart_soft, sc);

#ifdef RND_COM
        rnd_attach_source(&sc->rnd_source, device_xname(sc->sc_dev),
                          RND_TYPE_TTY, RND_FLAG_DEFAULT);
#endif

        /* if there are no enable/disable functions, assume the device
           is always enabled */
        if (!sc->enable)
                sc->enabled = 1;

        /* XXX configure register */
        /* xxx_config(sc) */

        SET(sc->sc_hwflags, COM_HW_DEV_OK);
}

static int
at91usart_param(struct tty *tp, struct termios *t)
{
        struct at91usart_softc *sc
                = device_lookup_private(&at91usart_cd, COMUNIT(tp->t_dev));
        int s;

        if (COM_ISALIVE(sc) == 0)
                return (EIO);

        if (t->c_ispeed && t->c_ispeed != t->c_ospeed)
                return (EINVAL);

        /*
         * For the console, always force CLOCAL and !HUPCL, so that the port
         * is always active.
         */
        if (ISSET(sc->sc_swflags, TIOCFLAG_SOFTCAR) ||
            ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                SET(t->c_cflag, CLOCAL);
                CLR(t->c_cflag, HUPCL);
        }

        /*
         * If there were no changes, don't do anything.  This avoids dropping
         * input and improves performance when all we did was frob things like
         * VMIN and VTIME.
         */
        if (tp->t_ospeed == t->c_ospeed &&
            tp->t_cflag == t->c_cflag)
                return (0);

        s = spltty();

        sc->sc_brgr = (AT91_MSTCLK / 16 + t->c_ospeed / 2) / t->c_ospeed;
        
        /* And copy to tty. */
        tp->t_ispeed = 0;
        tp->t_ospeed = t->c_ospeed;
        tp->t_cflag = t->c_cflag;
        at91usart_set(sc);

        splx(s);

        /*
         * Update the tty layer's idea of the carrier bit.
         * We tell tty the carrier is always on.
         */
        (void) (*tp->t_linesw->l_modem)(tp, 1);

#ifdef COM_DEBUG
        if (com_debug)
                comstatus(sc, "comparam ");
#endif

        /* tell the upper layer about hwflow.. */
        if (sc->hwflow)
                (*sc->hwflow)(sc, t->c_cflag);

        return (0);
}

static int
at91usart_hwiflow(struct tty *tp, int block)
{
        if (block) {
                /* tty discipline wants to block */
        } else {
                /* tty discipline wants to unblock */
        }
        return (0);
}

static __inline void
at91usart_start_tx(struct at91usart_softc *sc)
{
        if (!sc->start_tx)
                at91usart_writereg(sc, US_PDC + PDC_PTCR, PDC_PTCR_TXTEN);
        else
                (*sc->start_tx)(sc);
}

static __inline void
at91usart_stop_tx(struct at91usart_softc *sc)
{
        if (!sc->stop_tx)
                at91usart_writereg(sc, US_PDC + PDC_PTCR, PDC_PTCR_TXTDIS);
        else
                (*sc->stop_tx)(sc);
}

static __inline void
at91usart_rx_started(struct at91usart_softc *sc)
{
        if (sc->rx_started)
                (*sc->rx_started)(sc);
}

static __inline void
at91usart_rx_stopped(struct at91usart_softc *sc)
{
        if (sc->rx_stopped)
                (*sc->rx_stopped)(sc);
}

static __inline void
at91usart_rx_rts_ctl(struct at91usart_softc *sc, int enabled)
{
        if (sc->rx_rts_ctl)
                (*sc->rx_rts_ctl)(sc, enabled);
}

static void
at91usart_filltx(struct at91usart_softc *sc)
{
        struct tty *tp = sc->sc_tty;
        int len;
        void *dst;

        // post write handler
        AT91PDC_FIFO_POSTWRITE(sc->sc_iot, sc->sc_ioh, sc->sc_dmat, US_PDC,
                                &sc->sc_tx_fifo);

        // copy more data to fifo:
        if (sc->sc_tbc > 0
            && (dst = AT91PDC_FIFO_WRPTR(&sc->sc_tx_fifo, &len)) != NULL) {
                // copy data to fifo
                if (len > sc->sc_tbc)
                        len = sc->sc_tbc;
                memcpy(dst, sc->sc_tba, len);
                sc->sc_tba += len;
                if ((sc->sc_tbc -= len) <= 0)
                        CLR(tp->t_state, TS_BUSY);
                // update fifo
                AT91PDC_FIFO_WRITTEN(&sc->sc_tx_fifo, len);
                // tell tty interface we've sent some bytes
                ndflush(&tp->t_outq, len);
        }

        // start sending data...
        if (AT91PDC_FIFO_PREWRITE(sc->sc_iot, sc->sc_ioh, sc->sc_dmat,
                                   US_PDC, &sc->sc_tx_fifo, PDC_BLOCK_SIZE)) {
                at91usart_start_tx(sc);
                SET(sc->sc_ier, US_CSR_TXEMPTY | US_CSR_ENDTX);
        } else {
                CLR(sc->sc_ier, US_CSR_ENDTX);
        }
}

static void
at91usart_start(struct tty *tp)
{
        struct at91usart_softc *sc
                = device_lookup_private(&at91usart_cd, COMUNIT(tp->t_dev));
        int s;

        if (COM_ISALIVE(sc) == 0) {
                DPRINTFN(5, ("%s: %s / COM_ISALIVE == 0\n", device_xname(sc->sc_dev), __FUNCTION__));
                return;
        }

        s = spltty();
        if (ISSET(tp->t_state, TS_BUSY | TS_TIMEOUT | TS_TTSTOP)) {
                DPRINTFN(5, ("%s: %s: TS_BUSY || TS_TIMEOUT || TS_TTSTOP\n", device_xname(sc->sc_dev), __FUNCTION__));
                goto out;
        }

        if (!ttypull(tp))
                goto out;

        /* Grab the first contiguous region of buffer space. */
        {
                u_char *tba;
                int tbc;

                tba = tp->t_outq.c_cf;
                tbc = ndqb(&tp->t_outq, 0);

                sc->sc_tba = tba;
                sc->sc_tbc = tbc;
        }

        SET(tp->t_state, TS_BUSY);

        /* Output the first chunk of the contiguous buffer. */
        at91usart_filltx(sc);
        at91usart_writereg(sc, US_IER, sc->sc_ier);
        DPRINTFN(5, ("%s: %s, ier=%08x (csr=%08x)\n", device_xname(sc->sc_dev), __FUNCTION__, sc->sc_ier, at91usart_readreg(sc, US_CSR)));

out:
        splx(s);

        return;
}

static __inline__ void
at91usart_break(struct at91usart_softc *sc, int onoff)
{
        at91usart_writereg(sc, US_CR, onoff ? US_CR_STTBRK : US_CR_STPBRK);
}

static void
at91usart_shutdown(struct at91usart_softc *sc)
{
        int s;

        s = spltty();

        /* turn of dma */
        at91usart_writereg(sc, US_PDC + PDC_PTCR, PDC_PTCR_TXTDIS | PDC_PTCR_RXTDIS);
        at91usart_writereg(sc, US_PDC + PDC_TNCR, 0);
        at91usart_writereg(sc, US_PDC + PDC_TCR, 0);
        at91usart_writereg(sc, US_PDC + PDC_RNCR, 0);
        at91usart_writereg(sc, US_PDC + PDC_RCR, 0);

        /* Turn off interrupts. */
        at91usart_writereg(sc, US_IDR, -1);

        /* Clear any break condition set with TIOCSBRK. */
        at91usart_break(sc, 0);
        at91usart_set(sc);

        if (sc->disable) {
#ifdef DIAGNOSTIC
                if (!sc->enabled)
                        panic("at91usart_shutdown: not enabled?");
#endif
                (*sc->disable)(sc);
                sc->enabled = 0;
        }
        splx(s);
}

int
at91usart_open(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct at91usart_softc *sc;
        struct tty *tp;
        int s;
        int error;

        sc = device_lookup_private(&at91usart_cd, COMUNIT(dev));
        if (sc == NULL || !ISSET(sc->sc_hwflags, COM_HW_DEV_OK))
                return (ENXIO);

        if (!device_is_active(sc->sc_dev))
                return (ENXIO);

#ifdef KGDB
        /*
         * If this is the kgdb port, no other use is permitted.
         */
        if (ISSET(sc->sc_hwflags, COM_HW_KGDB))
                return (EBUSY);
#endif

        tp = sc->sc_tty;

        if (kauth_authorize_device_tty(l->l_cred, KAUTH_DEVICE_TTY_OPEN, tp))
                return (EBUSY);

        s = spltty();

        /*
         * Do the following iff this is a first open.
         */
        if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
                struct termios t;

                tp->t_dev = dev;

                if (sc->enable) {
                        if ((*sc->enable)(sc)) {
                                splx(s);
                                printf("%s: device enable failed\n",
                                       device_xname(sc->sc_dev));
                                return (EIO);
                        }
                        sc->enabled = 1;
#if 0
/* XXXXXXXXXXXXXXX */
                        com_config(sc);
#endif
                }

                /* reset fifos: */
                AT91PDC_RESET_FIFO(sc->sc_iot, sc->sc_ioh, sc->sc_dmat, US_PDC, &sc->sc_rx_fifo, 0);
                AT91PDC_RESET_FIFO(sc->sc_iot, sc->sc_ioh, sc->sc_dmat, US_PDC, &sc->sc_tx_fifo, 1);

                /* reset receive */
                at91usart_writereg(sc, US_CR, US_CR_RSTSTA | US_CR_STTTO);

                /* Turn on interrupts. */
                sc->sc_ier = US_CSR_ENDRX|US_CSR_RXBUFF|US_CSR_TIMEOUT|US_CSR_RXBRK;
                at91usart_writereg(sc, US_IER, sc->sc_ier);

                /* enable DMA: */
                at91usart_writereg(sc, US_PDC + PDC_PTCR, PDC_PTCR_RXTEN);

                /*
                 * Initialize the termios status to the defaults.  Add in the
                 * sticky bits from TIOCSFLAGS.
                 */
                t.c_ispeed = 0;
/*              if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                        t.c_ospeed = usart_cn_sc.sc_ospeed;
                        t.c_cflag = usart_cn_sc.sc_cflag;
                } else*/ {
                        t.c_ospeed = TTYDEF_SPEED;
                        t.c_cflag = TTYDEF_CFLAG;
                }
                if (ISSET(sc->sc_swflags, TIOCFLAG_CLOCAL))
                        SET(t.c_cflag, CLOCAL);
                if (ISSET(sc->sc_swflags, TIOCFLAG_CRTSCTS))
                        SET(t.c_cflag, CRTSCTS);
                if (ISSET(sc->sc_swflags, TIOCFLAG_MDMBUF))
                        SET(t.c_cflag, MDMBUF);

                /* Make sure at91usart_param() will do something. */
                tp->t_ospeed = 0;
                (void) at91usart_param(tp, &t);
                tp->t_iflag = TTYDEF_IFLAG;
                tp->t_oflag = TTYDEF_OFLAG;
                tp->t_lflag = TTYDEF_LFLAG;
                ttychars(tp);
                ttsetwater(tp);

                /* and unblock. */
                CLR(sc->sc_rx_flags, RX_ANY_BLOCK);

#ifdef COM_DEBUG
                if (at91usart_debug)
                        comstatus(sc, "at91usart_open  ");
#endif

        }
        
        splx(s);

        error = ttyopen(tp, COMDIALOUT(dev), ISSET(flag, O_NONBLOCK));
        if (error)
                goto bad;

        error = (*tp->t_linesw->l_open)(dev, tp);
        if (error)
                goto bad;

        return (0);

bad:
        if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
                /*
                 * We failed to open the device, and nobody else had it opened.
                 * Clean up the state as appropriate.
                 */
                at91usart_shutdown(sc);
        }

        return (error);
}

int
at91usart_close(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct at91usart_softc *sc = device_lookup_private(&at91usart_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        /* XXX This is for cons.c. */
        if (!ISSET(tp->t_state, TS_ISOPEN))
                return (0);

        (*tp->t_linesw->l_close)(tp, flag);
        ttyclose(tp);

        if (COM_ISALIVE(sc) == 0)
                return (0);

        if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
                /*
                 * Although we got a last close, the device may still be in
                 * use; e.g. if this was the dialout node, and there are still
                 * processes waiting for carrier on the non-dialout node.
                 */
                at91usart_shutdown(sc);
        }

        return (0);
}

int
at91usart_read(dev_t dev, struct uio *uio, int flag)
{
        struct at91usart_softc *sc = device_lookup_private(&at91usart_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        if (COM_ISALIVE(sc) == 0)
                return (EIO);
 
        return ((*tp->t_linesw->l_read)(tp, uio, flag));
}

int
at91usart_write(dev_t dev, struct uio *uio, int flag)
{
        struct at91usart_softc *sc = device_lookup_private(&at91usart_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        if (COM_ISALIVE(sc) == 0)
                return (EIO);
 
        return ((*tp->t_linesw->l_write)(tp, uio, flag));
}

int
at91usart_poll(dev_t dev, int events, struct lwp *l)
{
        struct at91usart_softc *sc = device_lookup_private(&at91usart_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        if (COM_ISALIVE(sc) == 0)
                return (EIO);
 
        return ((*tp->t_linesw->l_poll)(tp, events, l));
}

struct tty *
at91usart_tty(dev_t dev)
{
        struct at91usart_softc *sc = device_lookup_private(&at91usart_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        return (tp);
}

int
at91usart_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
        struct at91usart_softc *sc = device_lookup_private(&at91usart_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;
        int error;
        int s;

        if (COM_ISALIVE(sc) == 0)
                return (EIO);

        error = (*tp->t_linesw->l_ioctl)(tp, cmd, data, flag, l);
        if (error != EPASSTHROUGH)
                return (error);

        error = ttioctl(tp, cmd, data, flag, l);
        if (error != EPASSTHROUGH)
                return (error);

        error = 0;

        s = spltty();

        switch (cmd) {
        case TIOCSBRK:
                at91usart_break(sc, 1);
                break;

        case TIOCCBRK:
                at91usart_break(sc, 0);
                break;

        case TIOCGFLAGS:
                *(int *)data = sc->sc_swflags;
                break;

        case TIOCSFLAGS:
                error = kauth_authorize_device_tty(l->l_cred,
                    KAUTH_DEVICE_TTY_PRIVSET, tp); 
                if (error)
                        break;
                sc->sc_swflags = *(int *)data;
                break;

        default:
                error = EPASSTHROUGH;
                break;
        }

        splx(s);

        return (error);
}

/*
 * Stop output on a line.
 */
void
at91usart_stop(struct tty *tp, int flag)
{
        struct at91usart_softc *sc
                = device_lookup_private(&at91usart_cd, COMUNIT(tp->t_dev));
        int s;

        s = spltty();
        if (ISSET(tp->t_state, TS_BUSY)) {
                /* Stop transmitting at the next chunk. */
                sc->sc_tbc = 0;
                if (!ISSET(tp->t_state, TS_TTSTOP))
                        SET(tp->t_state, TS_FLUSH);
        }
        splx(s);
}

#if 0
static u_int
cflag2lcrhi(tcflag_t cflag)
{
        uint32_t        mr;

        switch (cflag & CSIZE) {
        default:
                mr = 0x0;
                break;
        }
#if 0
        mr |= (cflag & PARENB) ? LinCtrlHigh_PEN : 0;
        mr |= (cflag & PARODD) ? 0 : LinCtrlHigh_EPS;
        mr |= (cflag & CSTOPB) ? LinCtrlHigh_STP2 : 0;
        mr |= LinCtrlHigh_FEN;  /* FIFO always enabled */
#endif
        mr |= USART_MR_PAR_NONE;
        return (mr);
}
#endif


static void
at91usart_set(struct at91usart_softc *sc)
{
        at91usart_writereg(sc, US_MR, US_MR_CHRL_8 | US_MR_PAR_NONE | US_MR_NBSTOP_1);
        at91usart_writereg(sc, US_BRGR, sc->sc_brgr);
        at91usart_writereg(sc, US_CR, US_CR_TXEN | US_CR_RXEN); // @@@ just in case
}

#if     NOTYET
int
at91usart_cn_attach(bus_space_tag_t iot, bus_addr_t iobase, bus_space_handle_t ioh,
                    uint32_t mstclk, int ospeed, tcflag_t cflag)
{
        cn_tab = &at91usart_cons;
        cn_init_magic(&at91usart_cnm_state);
        cn_set_magic("\047\001");

        usart_cn_sc.sc_iot = iot;
        usart_cn_sc.sc_ioh = ioh;
        usart_cn_sc.sc_hwbase = iobase;
        usart_cn_sc.sc_ospeed = ospeed;
        usart_cn_sc.sc_cflag = cflag;

        USART_INIT(mstclk, ospeed);

        return (0);
}

void
at91usart_cn_probe(struct consdev *cp)
{
        cp->cn_pri = CN_REMOTE;
}

void
at91usart_cn_pollc(dev_t dev, int on)
{
        if (on) {
                // enable polling mode
                USARTREG(US_IDR) = USART_INT_RXRDY;
        } else {
                // disable polling mode
                USARTREG(US_IER) = USART_INT_RXRDY;
        }
}

void
at91usart_cn_putc(dev_t dev, int c)
{
        int                     s;
#if 0
        bus_space_tag_t         iot = usart_cn_sc.sc_iot;
        bus_space_handle_t      ioh = usart_cn_sc.sc_ioh;
#endif
        s = spltty();

        USART_PUTC(c);

#ifdef DEBUG
        if (c == '\r') {
                while((USARTREG(USART_SR) & USART_SR_TXEMPTY) == 0)
                        ;
        }
#endif

        splx(s);
}

int
at91usart_cn_getc(dev_t dev)
{
        int                     c, sr;
        int                     s;
#if 0
        bus_space_tag_t         iot = usart_cn_sc.sc_iot;
        bus_space_handle_t      ioh = usart_cn_sc.sc_ioh;
#endif

        s = spltty();

        while ((c = USART_PEEKC()) == -1) {
          splx(s);
          s = spltty();
        }
                ;
        sr = USARTREG(USART_SR);
        if (ISSET(sr, USART_SR_FRAME) && c == 0) {
                USARTREG(USART_CR) = USART_CR_RSTSTA;   // reset status bits
                c = CNC_BREAK;
        }
        if (!db_active) {
                int cn_trapped __unused = 0;

                cn_check_magic(dev, c, at91usart_cnm_state);
        }
        splx(s);

        c &= 0xff;

        return (c);
}
#endif  /* NOTYET */

inline static void
at91usart_rxsoft(struct at91usart_softc *sc, struct tty *tp, unsigned csr)
{
        u_char *start, *get, *end;
        int cc;

        AT91PDC_FIFO_POSTREAD(sc->sc_iot, sc->sc_ioh, sc->sc_dmat, US_PDC,
                              &sc->sc_rx_fifo);

        if (ISSET(csr, US_CSR_TIMEOUT | US_CSR_RXBRK))
                at91usart_rx_stopped(sc);

        while ((start = AT91PDC_FIFO_RDPTR(&sc->sc_rx_fifo, &cc)) != NULL) {
                int (*rint)(int, struct tty *) = tp->t_linesw->l_rint;
                int code;

                if (!ISSET(csr, US_CSR_TIMEOUT | US_CSR_RXBRK))
                        at91usart_rx_started(sc);

                for (get = start, end = start + cc; get < end; get++) {
                        code = *get;
                        if ((*rint)(code, tp) == -1) {
                                /*
                                 * The line discipline's buffer is out of space.
                                 */
                                if (!ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED)) {
                                        /*
                                         * We're either not using flow control, or the
                                         * line discipline didn't tell us to block for
                                         * some reason.  Either way, we have no way to
                                         * know when there's more space available, so
                                         * just drop the rest of the data.
                                         */
                                        get = end;
                                        printf("%s: receive missing data!\n",
                                             device_xname(sc->sc_dev));
                                } else {
                                        /*
                                         * Don't schedule any more receive processing
                                         * until the line discipline tells us there's
                                         * space available (through comhwiflow()).
                                         * Leave the rest of the data in the input
                                         * buffer.
                                         */
                                        SET(sc->sc_rx_flags, RX_TTY_OVERFLOWED);
                                }
                                break;
                        }
                }

                // tell we've read some bytes...
                AT91PDC_FIFO_READ(&sc->sc_rx_fifo, get - start);

                if (ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED))
                        break;
        }

        // h/w flow control hook:
        if (ISSET(sc->sc_swflags, TIOCFLAG_CRTSCTS))
                at91usart_rx_rts_ctl(sc, (AT91PDC_FIFO_SPACE(&sc->sc_rx_fifo) > PDC_BLOCK_SIZE * 2));

        // write next pointer if USART is ready:
        if (AT91PDC_FIFO_PREREAD(sc->sc_iot, sc->sc_ioh, sc->sc_dmat, US_PDC,
                                  &sc->sc_rx_fifo, PDC_BLOCK_SIZE)) {
                SET(sc->sc_ier, US_CSR_ENDRX | US_CSR_RXBUFF | US_CSR_TIMEOUT | US_CSR_RXBRK);
        } else {
                CLR(sc->sc_ier, US_CSR_ENDRX | US_CSR_RXBUFF | US_CSR_TIMEOUT | US_CSR_RXBRK);
        }
}

inline static void
at91usart_txsoft(struct at91usart_softc *sc, struct tty *tp)
{
        at91usart_filltx(sc);
        if (!ISSET(tp->t_state, TS_BUSY))
                (*tp->t_linesw->l_start)(tp);
}


static void
at91usart_soft(void* arg)
{
        struct at91usart_softc *sc = arg;
        int s;
        u_int csr;

        if (COM_ISALIVE(sc) == 0)
                return;

        s = spltty();
        csr = sc->sc_csr;
        while (csr != 0) {
                if ((csr &= sc->sc_ier) == 0)
                        break;
//              splx(s);
                DPRINTFN(5, ("%s: %s / csr = 0x%08x\n", device_xname(sc->sc_dev), __FUNCTION__, csr));
                if (ISSET(csr, US_CSR_ENDRX | US_CSR_RXBUFF | US_CSR_TIMEOUT | US_CSR_RXBRK)) {
                        /* receive interrupt */
                        if (ISSET(csr, US_CSR_RXBRK)) {
                                // break received!
                                at91usart_writereg(sc, US_CR, US_CR_RSTSTA | US_CR_STTTO);
                        } else if (ISSET(csr, US_CSR_TIMEOUT)) {
                                // timeout received
                                at91usart_writereg(sc, US_CR, US_CR_STTTO);
                        }
                        at91usart_rxsoft(sc, sc->sc_tty, csr);
                }
                if (ISSET(csr, US_CSR_TXEMPTY)) {
                        at91usart_stop_tx(sc);
                        CLR(sc->sc_ier, US_CSR_TXEMPTY);
                        if (AT91PDC_FIFO_EMPTY(&sc->sc_tx_fifo)) {
                                // everything sent!
                                if (ISSET(sc->sc_tty->t_state, TS_FLUSH))
                                        CLR(sc->sc_tty->t_state, TS_FLUSH);
                        }
                }
                if (ISSET(csr, US_CSR_TXEMPTY | US_CSR_ENDTX)) {
                        /* transmit interrupt! */
                        at91usart_txsoft(sc, sc->sc_tty);
                }
//              s = spltty();
                csr = at91usart_readreg(sc, US_CSR);
        }
        sc->sc_csr = 0;
        at91usart_writereg(sc, US_IER, sc->sc_ier);     // re-enable interrupts
        splx(s);
}


static int
at91usart_intr(void* arg)
{
        struct at91usart_softc *sc = arg;
        u_int csr, imr;

        // get out if interrupts are not enabled
        imr = at91usart_readreg(sc, US_IMR);
        if (!imr)
                return 0;
        // get out if pending interrupt is not enabled
        csr = at91usart_readreg(sc, US_CSR);
        DPRINTFN(6,("%s: csr=%08X imr=%08X\n", device_xname(sc->sc_dev), csr, imr));
        if (!ISSET(csr, imr))
                return 0;

        // ok, we DO have some interrupts to serve! let softint do it
        sc->sc_csr = csr;
        at91usart_writereg(sc, US_IDR, -1);

        /* Wake up the poller. */
        softint_schedule(sc->sc_si);

        /* we're done for now */
        return (1);

}